Herbicidal compositions

ABSTRACT

The present invention relates to a method of controlling weeds using mixtures of non-selective herbicides and plant growth regulators. It also relates to mixtures of non-selective herbicides and plant growth regulators per se, and compositions comprising the same.

The present invention relates to a method of controlling weeds usingmixtures of non-selective herbicides and compounds regulating growth(“plant growth regulators”). It also relates to mixtures ofnon-selective herbicides and plant growth regulators per se, andcompositions comprising the same.

The protection of crops (from damage due to weeds and other vegetationthat inhibit crop growth, reduce quality and/or hinder farmingoperations) is a constantly recurring problem in agriculture and turfmanagement for professional home and garden use. In addition,aesthetically, it may be of interest to remove such unwanted weeds andvegetation, for example, when growing turf in areas such as golfcourses, lawns and public parks. To help combat these problems,researchers in the field of synthetic chemistry have produced anextensive variety of chemicals and chemical formulations effective inthe control of such unwanted growth. Chemical herbicides of many types,and having various modes of action, have been disclosed in theliterature and a large number are in commercial use. Commercialherbicides and some that are still in development are described in ‘ThePesticide Manual’, 14^(th) Edition, published 2006 by the British CropProtection Council.

Plant growth regulators are often used to regulate the growth anddevelopment of crop plants. For example, plant growth regulators areused to slow the development of a crop (such as oil seed rape) so thatit flowers at a desired time, reduce the height of a crop (such as incereals) so that it is less susceptible to lodging, increase nitrogenefficiency, regulate flowering and fruit set of a crop (such as fruittrees), and slow turfgrass growth rate to reduce mowing frequency.

There are several different classes of plant growth regulator. Knownclasses include azoles (such as uniconazole, and paclobutrazol),cyclohexane carboxylates (such as trinexapac-ethyl, andprohexadione-calcium), pyrimidinyl carbinols (such as flurprimidol, andancymidol), quarternary ammoniums (such as chlormequat-chloride, andmepiquat-chloride), and sulphonyl-amino phenyl-acetamides (such asmefluidide).

Plant growth regulators operate by various modes of action. For example,onium-type plant growth retardants such as chlormequat-chloride andmepiquat-chloride, that possess a positively charged ammonium,phosphonium or sulphonium group, function by blocking the synthesis ofgibberellin early in the biosynthetic pathway. Growth retardantscomprising a nitrogen-containing heterocycle, such as flurprimidol,paclobutrazol and uniconazole-P, act as inhibitors of monooxygenasesthat catalyse oxidative steps in gibberellin biosynthesis. Structuralmimics of 2-oxoglutaric acid, such as the acylcyclohexanedionestrinexapac-ethyl and prohexadione-calcium, interfere with the late stepsof gibberellin biosynthesis. Other plant growth regulators, such asmefluidide, inhibit cell division and differentiation.

In some cases, herbicidally active ingredients have been shown to bemore effective when mixed with other herbicides compared to when appliedindividually, and this is referred to as “synergism”, since thecombination demonstrates a potency or activity level exceeding thatwhich it would be expected to have based on knowledge of the individualpotencies of the components.

The present invention resides in the discovery that herbicides exhibitan improved herbicidal effect when applied in combination with plantgrowth regulators. In particular, it has been found that such mixtureshave a synergistic effect, providing quicker, better and longer-lastingherbicidal activity than the person skilled in the art would expectgiven the activity of each active ingredient when applied alone.

According to the present invention, there is provided a method forcontrolling weeds, comprising applying to the weeds or to the locuswhere the weeds are present, a mixture of one or more non-selectiveherbicides and one or more plant growth regulators in a synergisticallyeffective amount, or a composition comprising said mixture(s). Suitablythe mixture will comprise at least one non-selective herbicide and atleast one plant growth regulator.

The composition contains a herbicidally effective combination of anon-selective herbicide and a plant growth regulator. The term‘herbicide’ as used herein denotes a compound which controls or modifiesthe growth of plants. The term ‘non-selective’ refers to the spectrum ofplant species against which the herbicide is active, non-selectiveherbicides being active against all plant species. In the context of thepresent invention, it includes both herbicides that provide totalvegetative control, and also herbicides that have a very broad spectrumof activity such as PPO inhibiting herbicides. The term ‘synergisticallyeffective amount’ indicates the quantity of such compounds which iscapable of producing a controlling or modifying effect on the growth ofplants, where said effect is greater than the sum of the effectsobtained by applying each of the compounds individually. Controlling ormodifying effects include all deviation from natural development, forexample: killing, retardation, suppression, leaf burn, albinism,dwarfing and the like. For example, plants that are not killed are oftenstunted and non-competitive with flowering disrupted. The term ‘plants’refers to all physical parts of a plant, including seeds, seedlings,saplings, roots, tubers, stems, stalks, foliage and fruits.

Suitably the herbicide is a non-selective herbicide. Suitably, theherbicide belongs to a class selected from the group consisting of PS-Iinhibitors, EPSPS inhibitors, glutamine synthetase inhibitors and PPOinhibitors.

In one embodiment of the present invention, the herbicide is a PS-Iinhibitor. Such herbicides inhibit photosystem I. Suitably, the PS-Iinhibitor is diquat or paraquat.

In one embodiment of the present invention, the herbicide is aninhibitor of EPSPS. Such herbicides inhibit the enzyme5-enolpyruvateshikimate-3-phosphate-synthase, and consequently disruptamino acid synthesis. Suitably the EPSPS inhibitor is glyphosate. Asused herein, the term glyphosate includes agriculturally acceptablesalts or esters thereof.

In one embodiment of the present invention, the herbicide is aninhibitor of glutamine synthetase. Suitably, the herbicide is selectedfrom the group consisting of glufosinate-ammonium and bialaphos(bilanaphos).

In one embodiment of the present invention, the herbicide is a PPOinhibitor. Such herbicides inhibit the protoporphyrinogen IX oxidase, todisrupt cell membranes. The herbicide may be selected from one of thefollowing classes: diphenylether, phenylpyrazole, N-phenylphthalimide,thiadiazole, oxadiazole, triazolinone, oxazolidinedione andpyrimidindione. For example the herbicide may be acifluorfen-Na,bifenox, chlomethoxyfen, fluoroglycofen-ethyl, fomesafen, halosafen,lactofen, oxyfluorfen, fluazolate, pyraflufen-ethyl, cinidon-ethyl,flumioxazin, flumiclorac-pentyl, fluthiacet-methyl, thidiazimin,oxadiazon, oxadiargyl, azafenidin, carfentrazone-ethyl, sulfentrazone,pentoxazone, benzfendizone, butafenacil, saflufenacil, pyraclonil,profluazol or flufenpyr-ethyl. Suitably, the PPO inhibitor is selectedfrom the group consisting of sulfentrazone, oxyfluorfen, lactofen,oxadiazon, fomesafen, saflufenacil, and butafenacil. Suitably, the PPOinhibitor is fomesafen. Suitably, the PPO inhibitor is saflufenacil.

The present invention includes all herbicidally active forms of theabove compounds, such as salts, chelates and esters.

Any plant growth regulator may be used in accordance with the presentinvention. In one embodiment, the plant growth regulator is selectedfrom the group consisting of trinexapac-ethyl, prohexadione-calcium,paclobutrazol, uniconazole, mepiquat-chloride and chlormequat-chloride.

Suitably, the plant growth regulator is a gibberellin biosynthesisinhibitor. Suitably, the plant growth regulator is a class A gibberellinbiosynthesis inhibitor. Suitably, the plant growth regulator is a classB gibberellin biosynthesis inhibitor. In a preferred embodiment theplant growth regulator is trinexapac-ethyl, prohexadione-calcium orchlormequat-chloride. Suitably, the plant growth regulator istrinexapac-ethyl. Suitably, the plant growth regulator isprohexadione-calcium. Suitably, the plant growth regulator ischlormequat-chloride.

In accordance with the present invention, there may be mentionedmixtures comprising a non-selective herbicide and trinexapac-ethyl, orcompositions comprising the same. Suitably, the mixture for use in thepresent invention comprises trinexapac-ethyl and a PS-I inhibitor.Suitably, the mixture for use in the present invention comprisestrinexapac-ethyl and a EPSPS inhibitor. Suitably, the mixture for use inthe present invention comprises trinexapac-ethyl and a glutaminesynthetase inhibitor. Suitably, the mixture for use in the presentinvention comprises trinexapac-ethyl and a PPO inhibitor. Suitably, themixture for use in the present invention comprises trinexapac-ethyl inadmixture with one or more herbicides selected from the group consistingof glyphosate, glufosinate, diquat and paraquat.

The present invention may be used to control a large number ofagronomically important weeds, including monocotyledonous weeds anddicotyledonous weeds.

For example, the invention may be used to control dicotyledonous weedssuch as Abutilon spp., Ambrosia spp., Amaranthus spp., Chenopodium spp.,Euphorbia spp., Galium spp., Ipomoea spp., Polygonum spp., Sida spp.,Sinapis spp., Solanum spp., Stellaria spp., Taraxacum spp., Trifoliumspp., Veronica spp., Viola spp. and Xanthium spp.

The invention may also be used to control monocotyledonous weeds such asAgrostis spp., Alopecurus spp., Apera spp., Avena spp., Brachiaria spp.,Bromus spp., Digitaria spp., Echinochloa spp., Eleusine spp., Eriochloaspp., Leptochloa spp., Lolium spp., Ottochloa spp., Panicum spp.,Paspalum spp., Phalaris spp., Poa spp., Rottboellia spp., Setaria spp.,Sorghum spp., both intrinsically sensitive as well as resistant (e.g.ACCase and/or ALS resistant) biotypes of any of these grass weeds, aswell as broadleaf monocotyledonous weeds such as Commelina spp.,Monochoria spp., Sagittaria spp. and sedges such as Cyperus spp. andScirpus spp.

Suitably, the present invention is used to control monocot weeds, moresuitably grasses. In particular, the present invention is used tocontrol annual bluegrass (Poa annua), perennial ryegrass (Loliumperenne), wild oat (Avena fatua), downy brome (Bromus tectorum),shattercane (Sorghum bicolor), and/or yellow nutsedge (Cyperusesculentus).

In one embodiment of the present invention, the mixture comprisestrinexapac-ethyl and glyphosate in a synergistically effective amount.Suitably, said mixture is used for the control of dicotyledonous weeds.

In a further embodiment of the present invention, the mixture comprisestrinexapac-ethyl and paraquat in a synergistically effective amount.Suitably, said mixture is used for the control of grass weeds.

In a further embodiment of the present invention, the mixture comprisestrinexapac-ethyl and glufosinate in a synergistically effective amount.Suitably, said mixture is used for the control of warm season grassweeds.

In a further embodiment of the present invention, the mixture comprisestrinexapac-ethyl and fomesafen in a synergistically effective amount.Suitably, said mixture is used for the control of dicot and monocotweeds. More suitably, said mixture is used for the control of grassweeds.

For the purposes of the present invention, the term ‘weeds’ includesundesirable crop species such as volunteer crops, both conventional andgenetically altered, either by means of mutation or transgenicapproaches. For example, in the context of turf grass crops such as on agolf course, creeping bentgrass putting green turf can be considered a‘volunteer’ if found in a fairway section where a different variety ofgrass is being cultivated. The other grasses listed below can,similarly, be considered weeds when found in the wrong place.

The ‘locus’ is intended to include soil, seeds, and seedlings as well asestablished vegetation.

According to the present invention, there is provided a herbicidalcomposition comprising at least one non-selective herbicide and at leastone plant growth regulator in a synergistically effective amount. In oneembodiment, the herbicide belongs to a class selected from the groupconsisting of PS-I inhibitors, EPSPS inhibitors, glutamine synthetaseinhibitors and PPO inhibitors.

Suitably the non-selective herbicide in the herbicidal composition isselected from the group consisting of glyphosate, glufosinate, paraquatand fomesafen.

Suitably the plant growth regulator in the herbicidal composition isselected from the group consisting of trinexapac-ethyl,prohexadione-calcium, paclobutrazol, uniconazole, mepiquat-chloride andchlormequat-chloride. Suitably the plant growth regulator istrinexapac-ethyl, prohexadione-calcium or chlormequat-chloride.

Suitably the herbicidal composition of the present invention comprisestrinexapac-ethyl and glyphosate in a synergistically effective amount.Suitably the herbicidal composition of the present invention comprisestrinexapac-ethyl and paraquat in a synergistically effective amount.Suitably the herbicidal composition of the present invention comprisestrinexapac-ethyl and glufosinate in a synergistically effective amount.Suitably the herbicidal composition of the present invention comprisestrinexapac-ethyl and fomesafen in a synergistically effective amount.

In the compositions of this invention, the mixture ratio of herbicide toplant growth regulator at which the herbicidal effect is synergisticlies within the range of between about 1:1000 and about 1000:1.Suitably, the mixture ratio of herbicide to plant growth regulator isbetween about 1:100 and about 100:1. More suitably, the mixture ratio ofherbicide to plant growth regulator is between about 1:1 and about 1:10.For example, where the herbicide is mesotrione and the plant growthregulator is trinexapac-ethyl, a mixture ratio of between about 1:3 andabout 1:6 is preferred.

The rate at which the composition of the invention is applied willdepend upon the particular type of weed to be controlled, the degree ofcontrol required and the timing and method of application. In general,the compositions of the invention can be applied at an application rateof from 0.001 kilograms active ingredient/hectare (kg ai/ha) to about5.0 kg ai/ha, based on the total amount of active ingredient (mesotrioneand trinexapac-ethyl) in the composition. An application rate of fromabout 0.01 kg ai/ha to about 5.0 kg ai/ha is preferred, with anapplication rate of from about 0.05 kg ai/ha to 1.0 kg ai/ha beingespecially preferred. It is noted that the rates used in the examplesbelow are glasshouse rates and are lower than those normally applied inthe field as herbicide effects tend to be magnified in such conditions.

In a further aspect, the present invention provides a method ofcontrolling or modifying the growth of weeds comprising applying to thelocus of such weeds a herbicidally effective amount of a composition ofthe invention.

The benefits of the present invention are seen most when the herbicidalcomposition is applied to control weeds in growing crops of usefulplants: such as maize (including field corn, pop corn and sweet corn),cotton, winter and spring cereals (including wheat, barley, rye, oats),rice, potato, sugar/fodder beet, winter and spring rape, leguminouscrops (including soybeans), grain sorghum, plantation crops (includingbananas, fruit trees, oilpalm, rubber, tree nurseries, vines),sugarcane, vegetables (including asparagus, rhubarb, tomato), sunflower,various berries, flax, cool and warm season turf grasses, and others.

Cool season turfgrasses include, for example, bluegrasses (Poa L.), suchas Kentucky bluegrass (Poa pratensis L.), rough bluegrass (Poa trivialisL.), Canada bluegrass (Poa compressa L.) and annual bluegrass (Poa annuaL.); bentgrasses (Agrostis L.), such as creeping bentgrass (Agrostispalustris Huds.), colonial bentgrass (Agrostis tenius Sibth.), velvetbentgrass (Agrostis canina L.) and redtop (Agrostis alba L.); fescues(Festuca L.), such as tall fescue (Festuca arundinacea Schreb.), meadowfescue (Festuca elatior L.) and fine fescues such as creeping red fescue(Festuca rubra L.), chewings fescue (Festuca rubra var. commutataGaud.), sheep fescue (Festuca ovina L.) and hard fescue (Festucalongifolia); and ryegrasses (Lolium L.), such as perennial ryegrass(Lolium perenne L.) and annual (Italian) ryegrass (Lolium multiflorumLam.).

Warm season turfgrasses include, for example, Bermudagrasses (Cynodon L.C. Rich), including hybrid and common Bermudagrass; Zoysiagrasses(Zoysia Willd.), St. Augustinegrass (Stenotaphrum secundatum (Walt.)Kuntze); and centipedegrass (Eremochloa ophiuroides (Munro.) Hack.).

In addition ‘crops’ are to be understood to include those crops thathave been made tolerant to pests and pesticides, including herbicides orclasses of herbicides (and, suitably, the herbicides of the presentinvention), as a result of conventional methods of breeding or geneticengineering. Tolerance to herbicides means a reduced susceptibility todamage caused by a particular herbicide compared to conventional cropbreeds. Crops can be modified or bred so as to be tolerant, for exampleto EPSPS inhibitors such as glyphosate, or to glufosinate.

The composition of the present invention is useful in controlling thegrowth of undesirable vegetation by pre-emergence or post-emergenceapplication to the locus where control is desired, depending on the cropover which the combination is applied. In one embodiment, therefore, theherbicidal composition of the invention is applied as a pre-emergentapplication. In a further embodiment, the herbicidal composition of theinvention is applied as a post-emergent application.

The compounds of the invention may be applied either simultaneously orsequentially. If administered sequentially, the components may beadministered in any order in a suitable timescale, for example, with upto a week between the time of administering the first component and thetime of administering the last component. Suitably, the components areadministered within 24 hours. More suitably, the components areadministered within a few hours. Suitably, the components areadministered within one hour. Suitably, if administered sequentially,the plant growth regulator is applied first. If the components areadministered simultaneously, they may be administered separately or as atank mix or as a pre-formulated mixture of all the components or as apre-formulated mixture of some of the components tank mixed with theremaining components. In one embodiment the mixture or composition ofthe present invention may be applied to a crop as a seed treatment priorto planting.

In practice, the compositions of the invention are applied as aformulation containing the various adjuvants and carriers known to orused in the industry. The compositions of the invention may thus beformulated as granules, as wettable powders, as emulsifiableconcentrates, as powders or dusts, as flowables, as solutions, assuspensions or emulsions, or as controlled release forms such asmicrocapsules. These formulations may contain as little as about 0.5% toas much as about 95% or more by weight of active ingredient. The optimumamount for any given compound will depend on formulation, applicationequipment and nature of the plants to be controlled.

Wettable powders are in the form of finely divided particles whichdisperse readily in water or other liquid carriers. The particlescontain the active ingredient retained in a solid matrix. Typical solidmatrices include fuller's earth, kaolin clays, silicas and other readilywet organic or inorganic solids. Wettable powders normally contain about5% to about 95% of the active ingredient plus a small amount of wetting,dispersing or emulsifying agent.

Emulsifiable concentrates are homogeneous liquid compositionsdispersible in water or other liquid and may consist entirely of theactive compound with a liquid or solid emulsifying agent, or may alsocontain a liquid carrier, such as xylene, heavy aromatic naphthas,isophorone and other non-volatile organic solvents. In use, theseconcentrates are dispersed in water or other liquid and normally appliedas a spray to the area to be treated. The amount of active ingredientmay range from about 0.5% to about 95% of the concentrate.

Granular formulations include both extrudates and relatively coarseparticles and are usually applied without dilution to the area in whichsuppression of vegetation is desired. Typical carriers for granularformulations include fertiliser, sand, fuller's earth, attapulgite clay,bentonite clays, montmorillonite clay, vermiculite, perlite, calciumcarbonate, brick, pumice, pyrophyllite, kaolin, dolomite, plaster, woodflour, ground corn cobs, ground peanut hulls, sugars, sodium chloride,sodium sulphate, sodium silicate, sodium borate, magnesia, mica, ironoxide, zinc oxide, titanium oxide, antimony oxide, cryolite, gypsum,diatomaceous earth, calcium sulphate and other organic or inorganicmaterials which absorb or which can be coated with the active compound.Particularly suitable is a fertiliser granule carrier. Granularformulations normally contain about 5% to about 25% active ingredientswhich may include surface-active agents such as heavy aromatic naphthas,kerosene and other petroleum fractions, or vegetable oils; and/orstickers such as dextrins, glue or synthetic resins. The granularsubstrate material can be one of the typical carriers mentioned aboveand/or can be a fertiliser material e.g. urea/formaldehyde fertilisers,ammonium, liquid nitrogen, urea, potassium chloride, ammonium compounds,phosphorus compounds, sulphur, similar plant nutrients andmicronutrients and mixtures or combinations thereof. The herbicide andthe plant growth regulator may be homogeneously distributed throughoutthe granule or may be spray impregnated or absorbed onto the granulesubstrate after the granules are formed.

Encapsulated granules are generally porous granules with porousmembranes sealing the granule pore openings, retaining the activespecies in liquid form inside the granule pores. Granules typicallyrange from 1 millimetre to 1 centimetre, preferably 1 to 2 millimetresin diameter. Granules are formed by extrusion, agglomeration orprilling, or are naturally occurring. Examples of such materials arevermiculite, sintered clay, kaolin, attapulgite clay, sawdust andgranular carbon. Shell o membrane materials include natural andsynthetic rubbers, cellulosic materials, styrene-butadiene copolymers,polyacrylonitriles, polyacrylates, polyesters, polyamides, polyureas,polyurethanes and starch xanthates.

Dusts are free-flowing admixtures of the active ingredient with finelydivided solids such as talc, clays, flours and other organic andinorganic solids which act as dispersants and carriers.

Microcapsules are typically droplets or granules of the active materialenclosed in an inert porous shell which allows escape of the enclosedmaterial to the surroundings at controlled rates. Encapsulated dropletsare typically about 1 to 50 microns in diameter.

The enclosed liquid typically constitutes about 50 to 95% of the weightof the capsule and may include solvent in addition to the activecompound.

Other useful formulations for herbicidal applications include simplesolutions of the active ingredients in a solvent in which it iscompletely soluble at the desired concentration, such as acetone,alkylated naphthalenes, xylene and other organic solvents. Pressurisedsprayers, wherein the active ingredient is dispersed in finely-dividedform as a result of vaporisation of a low boiling dispersant solventcarrier, may also be used.

Many of the formulations described above include wetting, dispersing oremulsifying agents. Examples are alkyl and alkylaryl sulphonates andsulphates and their salts, polyhydric alcohols; polyethoxylatedalcohols, esters and fatty amines. These agents, when used, normallycomprise from 0.1% to 15% by weight of the formulation.

Suitable agricultural adjuvants and carriers, either formulated togetherand/or added separately, that are useful in formulating the compositionsof the invention in the formulation types described above are well knownto those skilled in the art. Suitable examples of the different classesare found in the non-limiting list below.

Liquid carriers that can be employed include water, toluene, xylene,petroleum naphtha, crop oils, AMS; acetone, methyl ethyl ketone,cyclohexanone, acetic anhydride, acetonitrile, acetophenone, amylacetate, 2-butanone, chlorobenzene, cyclohexane, cyclohexanol, alkylacetates, diacetonalcohol, 1,2-dichloropropane, diethanolamine,p-diethylbenzene, diethylene glycol, diethylene glycol abietate,diethylene glycol butyl ether, diethylene glycol ethyl ether, diethyleneglycol methyl ether, N,N-dimethyl formamide, dimethyl sulfoxide,1,4-dioxane, dipropylene glycol, dipropylene glycol methyl ether,dipropylene glycol dibenzoate, diproxitol, alkyl pyrrolidinone, ethylacetate, 2-ethyl hexanol, ethylene carbonate, 1,1,1-trichloroethane,2-heptanone, alpha pinene, d-limonene, ethylene glycol, ethylene glycolbutyl ether, ethylene glycol methyl ether, gamma-butyrolactone,glycerol, glycerol diacetate, glycerol monoacetate, glycerol triacetate,hexadecane, hexylene glycol, isoamyl acetate, isobornyl acetate,isooctane, isophorone, isopropyl benzene, isopropyl myristate, lacticacid, laurylamine, mesityl oxide, methoxy-propanol, methyl isoamylketone, methyl isobutyl ketone, methyl laurate, methyl octanoate, methyloleate, methylene chloride, m-xylene, n-hexane, n-octylamine,octadecanoic acid, octyl amine acetate, oleic acid, oleylamine,o-xylene, phenol, polyethylene glycol (PEG400), propionic acid,propylene glycol, propylene glycol monomethyl ether, p-xylene, toluene,triethyl phosphate, triethylene glycol, xylene sulfonic acid, paraffin,mineral oil, trichloroethylene, perchloroethylene, ethyl acetate, amylacetate, butyl acetate, methanol, ethanol, isopropanol, and highermolecular weight alcohols such as amyl alcohol, tetrahydrofurfurylalcohol, hexanol, octanol, etc. ethylene glycol, propylene glycol,glycerine, N-methyl-2-pyrrolidinone, and the like. Water is generallythe carrier of choice for the dilution of concentrates.

Suitable solid carriers include talc, titanium dioxide, pyrophylliteclay, silica, attapulgite clay, kieselguhr, chalk, diatomaxeous earth,lime, calcium carbonate, bentonite clay, fuller's earth, fertiliser,cotton seed hulls, wheat flour, soybean flour, pumice, wood flour,walnut shell flour, lignin and the like.

A broad range of surface-active agents are advantageously employed inboth said liquid and solid compositions, especially those designed to bediluted with carrier before application. The surface-active agents canbe anionic, cationic, non-ionic or polymeric in character and can beemployed as emulsifying agents, wetting agents, suspending agents or forother purposes. Typical surface active agents include salts of alkylsulfates, such as diethanolammonium lauryl sulphate; alkylarylsulfonatesalts, such as calcium dodecylbenzenesulfonate; alkylphenol-alkyleneoxide addition products, such as nonylphenol-C.sub. 18 ethoxylate;alcohol-alkylene oxide addition products, such as tridecylalcohol-C.sub. 16 ethoxylate; soaps, such as sodium stearate;alkylnaphthalenesulfonate salts, such as sodiumdibutylnaphthalenesulfonate; dialkyl esters of sulfosuccinate salts,such as sodium di(2-ethylhexyl) sulfosuccinate; sorbitol esters, such assorbitol oleate; quaternary amines, such as lauryl trimethylammoniumchloride; polyethylene glycol esters of fatty acids, such aspolyethylene glycol stearate; block copolymers of ethylene oxide andpropylene oxide; and salts of mono and dialkyl phosphate esters.

Other adjuvants commonly utilized in agricultural compositions includecrystallisation inhibitors, viscosity modifiers, suspending agents,spray droplet modifiers, pigments, antioxidants, foaming agents,light-blocking agents, compatibilizing agents, antifoam agents,sequestering agents, neutralising agents and buffers, corrosioninhibitors, dyes, odorants, spreading agents, penetration aids,micronutrients, emollients, lubricants, sticking agents, and the like.The compositions can also be formulated with liquid fertilizers orsolid, particulate fertiliser carriers such as ammonium nitrate, ureaand the like.

An important factor in influencing the usefulness of a given mixture ofa herbicide and a plant growth regulator is its tolerance towards crops(“phytotoxicity”). In most cases, this will be determined by the choiceof herbicide. In some cases, a beneficial crop is susceptible to theeffects of the herbicide. To be effective, an herbicide must causeminimal damage (preferably no damage) to the beneficial crop whilemaximizing damage to weed species which infest the locus of the crop. Topreserve the beneficial aspects of herbicide use and to minimize cropdamage, it is known to apply herbicides in combination with anantidote/safener, if necessary. As used here in ‘antidote’ describes acompound which has the safening effect of establishing herbicideselectivity, i.e. continued herbicidal phytotoxicity to weed species bythe herbicide and reduced or non-phytotoxicity to the cultivated cropspecies. The term ‘antidotally effective amount’ describes an amount ofan antidote compound which counteracts to some degree a phytotoxicresponse of a beneficial crop to an herbicide. If necessary or desiredfor a particular application or crop, the composition of the presentinvention may contain an antidotally effective amount of an antidote forthe herbicides of the invention. Those skilled in the art will befamiliar with antidotes which are suitable for use with particularherbicides and plant growth regulators and can readily determine anantidotally effective amount for a particular mixture. In oneembodiment, the present invention is used to control weeds in crops thatare resistant to the herbicide, so that a safener is not required.

Suitably the present invention is used to control weeds in crops thatare resistant to the herbicidal mixture or composition. For example, itmay be used to control weeds in glyphosate tolerant corn. In oneembodiment of the present invention, there is provided a method forcontrolling weeds in a crop, comprising applying to the crop aherbicidal composition comprising a non-selective herbicide and a plantgrowth regulator in a synergistically effective amount, wherein the cropis resistant to the non-selective herbicide.

In addition, further, other biocidally active ingredients orcompositions may be combined with the herbicidal composition of thisinvention. For example, the compositions may contain, in addition to theherbicide and plant growth regulator, other herbicides, insecticides,fungicides, bactericides, acaracides, nematicides and/or plant growthregulators, in order to broaden the spectrum of activity.

Each of the above formulations can be prepared as a package containingthe herbicides together with other ingredients of the formulation(diluents, emulsifiers, surfactants, etc.). The formulations can also beprepared by a tank mix method, in which the ingredients are obtainedseparately and combined at the grower site.

These formulations can be applied to the areas where control is desiredby conventional methods. Dust and liquid compositions, for example, canbe applied by the use of power-dusters, broom and hand sprayers andspray dusters. The formulations can also be applied from airplanes as adust or a spray or by rope wick applications. To modify or controlgrowth of germinating seeds or emerging seedlings, dust and liquidformulations can be distributed in the soil to a depth of at leastone-half inch below the soil surface or applied to the soil surfaceonly, by spraying or sprinkling. The formulations can also be applied byaddition to irrigation water. This permits penetration of theformulations into the soil together with the irrigation water. Dustcompositions, granular compositions or liquid formulations applied tothe surface of the soil can be distributed below the surface of the soilby conventional means such as disking, dragging or mixing operations.

The present invention can be used in any situation in which weed controlis desired, for example in agriculture, on golf courses, or in gardens.

The following examples are for illustrative purposes only. The examplesare not intended as necessarily representative of the overall testingperformed and are not intended to limit the invention in any way. As oneskilled in the art is aware, in herbicidal testing, a significant numberof factors that are not readily controllable can affect the results ofindividual tests and render them non-reproducible. For example, theresults may vary depending on environmental factors, such as amount ofsunlight and water, soil type, pH of the soil, temperature and humidity,among others. Also, the depth of planting, the application rate ofindividual and combined herbicides, the application rate of anyantidote, and the ratio of the individual herbicides to one anotherand/or to an antidote as well as the nature of crops or weeds beingtested can affect the results of the test. Results may vary from crop tocrop within the crop varieties.

EXAMPLES

In the following tests, herbicides were applied at reduced field ratesbecause herbicide effects are magnified in a glasshouse environment. Therates tested were selected to give between about 50 and 70% control withherbicides applied alone, so that any synergistic effect could bereadily detected when testing mixtures.

Example 1 Control of Barnyard Grass with Mesotrione and Trinexapac-EthylApplied Post-Emergence

A glasshouse trial was carried out. Barnyard grass seeds were sown intostandard glasshouse potting mix (1:1 v/v Promix:Vero sand soil)contained in 10 cm square plastic pots. Treatments were replicated threetimes. Mesotrione (in the form Callisto® 480SE) (MST) was appliedpost-emergence to barnyard grass (Echinochloa crus-galli) at either 12.5g ai/ha or 25 g ai/ha with or without trinexapac-ethyl (in the form ofPalisade®) (TXP). When used, trinexapac-ethyl was applied at a rate of200 g ai/ha or 400 g ai/ha. The adjuvant system was X-77 at 0.1% v/v indeionised water. 200 litres of herbicide/adjuvant system was used perhectare. General weed control was evaluated at 6-9 and 14-18 days aftertreatment (DAT). It is noted that all herbicides were applied at reducedfield rates because herbicide effects are magnified in a glasshouseenvironment. Rates were chosen to give a 50 to 70% level of control withherbicides applied alone as this allows for detection of any synergisticeffect when tank mixtures are used.

Table 1 shows the results, as evaluated using the Colby formula. Theexpected result for (Y+Z) is (Y+Z)−(Y×Z/100) where Y and Z are the‘observed’ results for Y and Z on their own. Control from the tankmixture is synergistic if the actual result is significantly higher thanthe expected result (significance based on Student-Newman-Keuls multiplerange test).

TABLE 1 MST at 12.5 MST at 25 Rate (g g ai/ha g ai/ha ai/ha) A E A E TXP200 38* 7 40* 25 TXP 400 47* 25 57* 40 A = actual weed control value; E= expected weed control value (calculated using the Colby formula); *=synergy

Using the Colby formula and Student-Newman-Keuls multiple range test,synergy was seen at both the high and low rates of mesotrione and thelow and high rates of trinexapac-ethyl when a combination oftrinexapac-ethyl and mesotrione was used to control barnyard grass.

Example 2 Control of Giant Foxtail with Mesotrione and Trinexapac-EthylApplied Post-Emergence

A glasshouse trial was carried out as described in Example 1,substituting barnyard grass for Setaria faberi (giant foxtail). Therates used, and results obtained, are indicated in Table 2 below.

TABLE 2 MST at 25 MST at 50 MST at 100 MST at 200 Rate (g g ai/ha gai/ha g ai/ha g ai/ha ai/ha) A E A E A E A E TXP 200 35.0* 32.5 32.532.5 35.0* 32.5 46.3* 32.5 TXP 400 36.3 45.0 45.0 54.0 48.8* 45.0 55.0*45.0 TXP 800 51.3* 43.8 43.8 43.8 53.8* 43.8 58.8* 43.8 A = actual weedcontrol value; E = expected weed control value (calculated using theColby formula); *= synergy

Synergy in control of giant foxtail was seen at many of the ratecombinations tested, but especially for high rates of mesotrione incombination with all rates of trinexapac-ethyl tested.

Example 3 Control of Large Crabgrass with Mesotrione andTrinexapac-Ethyl Applied Post-Emergence

A glasshouse trial was carried out as described in Example 1,substituting barnyard grass for Digitaria sanguinalis (large crabgrass).The rates used, and results obtained, are indicated in Table 3 below.

TABLE 3 MST at 25 MST at 50 MST at 100 MST at 200 Rate (g g ai/ha gai/ha g ai/ha g ai/ha ai/ha) A E A E A E A E TXP 200 52.5* 24.9 73.8*44.5 77.0* 55.0 87.5* 68.4 TXP 400 45.0* 30.0 60.0* 48.3 75.8* 58.093.3* 70.5 TXP 800 60.0* 47.2 72.5* 61.0 81.3* 68.3 91.3* 77.8 A =actual weed control value; E = expected weed control value (calculatedusing the Colby formula); *= synergy

Synergy in control of large crabgrass was seen at all rate combinationstested.

Example 4 Control of Fall Panicum with Mesotrione and Trinexapac-EthylApplied Post-Emergence

A glasshouse trial was carried out as described in Example 1,substituting barnyard grass for Panicum dichotomiflorum (fall panicum).The rates used, and results obtained, are indicated in Table 4 below.

TABLE 4 MST at 25 MST at 50 MST at 100 MST at 200 Rate (g g ai/ha gai/ha g ai/ha g ai/ha ai/ha) A E A E A E A E TXP 200 27.5 36.5 23.8 38.236.3 41.6 58.8* 53.6 TXP 400 38.8* 32.9 40.0* 34.8 47.5* 38.4 62.5* 51.1TXP 800 43.8* 36.5 37.5 38.2 46.3* 41.6 68.8* 53.6 A = actual weedcontrol value; E = expected weed control value (calculated using theColby formula); *= synergy

Synergy in control of fall panicum was seen at many of the ratecombinations tested, but especially for high rates of mesotrione incombination with all rates of trinexapac-ethyl tested.

Example 5 Control of Goosegrass with Mesotrione and Trinexapac-EthylApplied Post-Emergence

A glasshouse trial was carried out as described in Example 1,substituting barnyard grass for Eleusine indica (goosegrass). The ratesused, and results obtained, are indicated in Table 5 below.

TABLE 5 MST at 25 MST at 50 MST at 100 MST at 200 Rate (g g ai/ha gai/ha g ai/ha g ai/ha ai/ha) A E A E A E A E TXP 200 53.8* 39.7 62.5*44.9 71.3* 44.9 83.8* 47.5 TXP 400 57.5* 50.4 64.5* 54.7 76.3* 54.785.0* 56.9 TXP 800 60.0* 56.9 65.0* 60.7 73.8* 60.7 90.0* 62.5 A =actual weed control value; E = expected weed control value (calculatedusing the Colby formula); *= synergy

Synergy in control of goosegrass was seen at all rate combinationstested.

Example 6 Weed Control with Mixtures of Non-Selective Herbicides andTrinexapac-Ethyl Applied Post-Emergence

A glasshouse trial was carried out to test the activity of variousherbicides (each at 2 different rates) in combination withtrinexapac-ethyl (at 3 different rates) against a variety of weedspecies. The dicot weeds tested were SINAR (Sinapis arvensis, wildmustard), CHEAL (Chenopodium album, common lambsquarter), IPOHE (Ipomoeahederacea, ivyleaf morningglory) and XANST (Xanthium strumarium, commoncocklebur). The monocot weeds tested were POANN (Poa annua, annualbluegrass), LOLPE (Lolium perenne, perennial ryegrass), AVEFA (Avenafatua, wild oat), BROTE (Bromus tectorum, downy brome), SORVU (Sorghumbicolor, shattercane) and CYPES (Cyperus esculentus, yellow nutsedge).

Seeds of each species were sown in standard potting mix in 50 cm plastictroughs. All compounds were applied as standard commercial formulations(Touchdown IQ® diammonium salt (SL360), Gramoxone Extra® (SL100), Basta®(SL200), Flex® (SL240), Moddus® (EC250)) at rates as listed in the tablebelow. The adjuvant system was X-77 at 0.1% v/v in deionised water. 500litres of herbicide/adjuvant system was used per hectare. General weedcontrol was evaluated at 14 days after treatment (DAT). It is noted thatall herbicides were applied at reduced field rates because herbicideeffects are magnified in a glasshouse environment. Rates were chosen togive a 50 to 70% level of control with herbicides applied alone as thisallows for detection of any synergistic effect when tank mixtures areused.

Tables 6 (dicot weeds), 7 (monocot weeds, cool season) and 8 (monocotweeds, warm season) shows the results, as evaluated using the Colbyformula. The expected result for (Y+Z) is (Y+Z)−(Y×Z/100) where Y and Zare the ‘observed’ results for Y and Z on their own. Control from thetank mixture is synergistic if the actual result is significantly higherthan the expected result (significance based on Student-Newman-Keulsmultiple range test).

TABLE 6 dicot weeds SINAR CHEAL IPOHE XANST Treatment (rates are in gai/ha) A E A E A E A E Glyphosate + Trinexapac (50 + 50 g) 70 n/a 0 030* 0  10** 40 Glyphosate + Trinexapac (100 + 50 g) 70 n/a 0 0 0 0 40 50Glyphosate + Trinexapac (50 + 100 g) 50 40 0 0 30* 0  40** 60Glyphosate + Trinexapac (100 + 100 g)  70* 40 0 0 30* 0 40 30Glyphosate + Trinexapac (50 + 200 g)  60* 40 0 0 20* 0 20 30Glyphosate + Trinexapac (100 + 200 g)  70* 40 0 0 70* 0 50 60 Paraquat +Trinexapac (50 + 50 g) 80 80 40  40  60* 40  90* 70 Paraquat +Trinexapac (100 + 50 g) 80 80 90* 70  100  100 100  90 Paraquat +Trinexapac (50 + 100 g) 70 70 80  n/a 30  40  90* 70 Paraquat +Trinexapac (100 + 100 g) 70 80 70  70   70** 100  80* 50 Paraquat +Trinexapac (50 + 200 g)  40** 70 70  n/a 30  40  90* 60 Paraquat +Trinexapac (100 + 200 g)  40** 80 90* 70   30** 100 100  90Glufosinate + Trinexapac (50 + 50 g) 50 50 0 0 0 0  70* 50 Glufosinate +Trinexapac (100 + 50 g) 60 60 0 0 0 0 70 60 Glufosinate + Trinexapac(50 + 100 g)  20** 40 M n/a 20* 0 90 90 Glufosinate + Trinexapac (100 +100 g)  80** 100 0 0 20* 0  90* 70 Glufosinate + Trinexapac (50 + 200 g)40 40 0 n/a 30* 0  80* 50 Glufosinate + Trinexapac (100 + 200 g)  80**100 0 0 70* 0  70* 40 Fomesafen + Trinexapac (10 + 50 g) 70 70 100  100 80* 40 60 60 Fomesafen + Trinexapac (40 + 50 g) 100  100 100*  80  80 80  70* 40 Fomesafen + Trinexapac (10 + 100 g) 80 90 M n/a 60* 40 40 40Fomesafen + Trinexapac (40 + 100 g) 100  100 100*  80  70  80 10 10Fomesafen + Trinexapac (10 + 200 g) 80 90 60  n/a 90* 40 70 60Fomesafen + Trinexapac (40 + 200 g)  80** 100 100*  80   60** 80 100* 60A = actual % control observed; E = expected % control (as calculatedusing Colby formula); M = missing datapoint; n/a = Colby calculation notpossible due to missing datapoint; *= significant synergy; **=significant antagonism

TABLE 7 monocot weeds, cool season POAAN LOLPE AVEFA BROTE Treatment(rates are in g ai/ha) A E A E A E A E Glyphosate + Trinexapac (50 + 50g) 0 0 0 0 0 0 0 0 Glyphosate + Trinexapac (100 + 50 g) 0 0 0 0 0 0 0 0Glyphosate + Trinexapac (50 + 100 g) 30* 0 0 0 0 0 0 0 Glyphosate +Trinexapac (100 + 100 g) 30* 0 0 0 0 0 0 0 Glyphosate + Trinexapac (50 +200 g) 0 0 0 0 0 0 0 0 Glyphosate + Trinexapac (100 + 200 g) 0 0 30* 0 00 0 0 Paraquat + Trinexapac (50 + 50 g) 0 10 0 10 0 0 50  40 Paraquat +Trinexapac (100 + 50 g)  20** 40 60  70  0** 20 70  60 Paraquat +Trinexapac (50 + 100 g) 10  10 40* 10 0 0 60* 40 Paraquat + Trinexapac(100 + 100 g)  10** 40 70  70 40* 20 70  60 Paraquat + Trinexapac (50 +200 g) 30* 10 30* 10 30* 0 60* 40 Paraquat + Trinexapac (100 + 200 g)70* 40 70  70 60* 20 70  60 Glufosinate + Trinexapac (50 + 50 g) 0 0 0 00 0 0 0 Glufosinate + Trinexapac (100 + 50 g) 0 0 0 0 0 0 0 0Glufosinate + Trinexapac (50 + 100 g) 0 0 0 0 0 0 0 0 Glufosinate +Trinexapac (100 + 100 g) 0 0 0 0 0 0 0 0 Glufosinate + Trinexapac (50 +200 g) 0 0 0 0 0 0 0 0 Glufosinate + Trinexapac (100 + 200 g) 20* 0 0 00 0 0 0 Fomesafen + Trinexapac (10 + 50 g) 0 0 10  0 0 10 40  30Fomesafen + Trinexapac (40 + 50 g) 20* 0 40* 0 60* 30 60  60 Fomesafen +Trinexapac (10 + 100 g) 0 0 0 0 30* 10 60* 30 Fomesafen + Trinexapac(40 + 100 g) 10  0 20* 0 50* 30 70  60 Fomesafen + Trinexapac (10 + 200g) 30* 0 20* 0 20  10 60* 30 Fomesafen + Trinexapac (40 + 200 g) 50* 030* 0 50* 30 70  60 A = actual % control observed; E = expected %control (as calculated using Colby formula); M = missing datapoint; n/a= Colby calculation not possible due to missing datapoint; *=significant synergy; **= significant antagonism

TABLE 8 monocot weeds, warm season SORVU CYPES Treatment (rates are in gai/ha) A E A E Glyphosate + Trinexapac (50 + 50 g) 20  20 0 10Glyphosate + Trinexapac (100 + 50 g)  20** 40  20** 50 Glyphosate +Trinexapac (50 + 100 g) 30  20 10* −10 Glyphosate + Trinexapac (100 +100 g) 40  40  40** 70 Glyphosate + Trinexapac (50 + 200 g) 40* 28 20 20 Glyphosate + Trinexapac (100 + 200 g) 40  46  20** 40 Paraquat +Trinexapac (50 + 50 g) 50  50 20* 0 Paraquat + Trinexapac (100 + 50 g)90  100 40  30 Paraquat + Trinexapac (50 + 100 g) 50  50 20* 0Paraquat + Trinexapac (100 + 100 g) 100  100 60  70 Paraquat +Trinexapac (50 + 200 g) 80* 55 30* 10 Paraquat + Trinexapac (100 + 200g)  80** 100 40  30 Glufosinate + Trinexapac (50 + 50 g) 0 0 20  20Glufosinate + Trinexapac (100 + 50 g) 40* 10 10  20 Glufosinate +Trinexapac (50 + 100 g) 40* 0  0* −20 Glufosinate + Trinexapac (100 +100 g) 50* 10 20  10 Glufosinate + Trinexapac (50 + 200 g) 40* 10 30  20Glufosinate + Trinexapac (100 + 200 g) 70* 19 30  40 Fomesafen +Trinexapac (10 + 50 g) 70* 50  0* −20 Fomesafen + Trinexapac (40 + 50 g)80* 50 30* −40 Fomesafen + Trinexapac (10 + 100 g) 70* 50 0 0Fomesafen + Trinexapac (40 + 100 g) 80* 50 0 −10 Fomesafen + Trinexapac(10 + 200 g) 70* 55 10* −20 Fomesafen + Trinexapac (40 + 200 g) 80* 5540* −60 A = actual % control observed; E = expected % control (ascalculated using Colby formula); M = missing datapoint; n/a = Colbycalculation not possible due to missing datapoint; *= significantsynergy; **= significant antagonism

Some variation in biological data is inevitable. However, the dataclearly demonstrates that synergy is observed when combiningnon-selective herbicides with trinexapac-ethyl, at various rates andagainst various different dicot and monocot weed species.

Although the invention has been described with reference to preferredembodiments and examples thereof, the scope of the present invention isnot limited only to those described embodiments. As will be apparent topersons skilled in the art, modifications and adaptations to theabove-described invention can be made without departing from the spiritand scope of the invention, which is defined and circumscribed by theappended claims. All publications cited herein are hereby incorporatedby reference in their entirety for all purposes to the same extent as ifeach individual publication were specifically and individually indicatedto be so incorporated by reference.

1. A method for controlling weeds, comprising applying to the weeds orto the locus where the weeds are present, a mixture of at least oneherbicide and at least one plant growth regulator in a synergisticallyeffective amount, or a composition comprising said mixture.
 2. A methodaccording to claim 1, wherein the herbicide belongs to a class selectedfrom the group consisting of HPPD inhibitors, PDS inhibitors, ACCaseinhibitors, ALS inhibitors, PS-I and PS-II inhibitors, EPSPS inhibitors,glutamine synthetase inhibitors, synthetic auxins, PPO inhibitors,cellulose synthase inhibitors, microtubule assembly inhibitors, andVLCFA inhibitors.
 3. A method according to claim 2, wherein theherbicide is an HPPD inhibitor.
 4. A method according to claim 3,wherein the herbicide is selected from the group consisting ofmesotrione, sulcotrione, benoxfenap, isoxachlortole, isoxaflutole,pyrazolynate, pyrazoxyfen, benzobicyclon, ketospiradox, tembotrione,topramezone, and a compound of formula I


5. A method according to claim 2, wherein the herbicide is a PDSinhibitor.
 6. A method according to claim 5, wherein the herbicide isselected from the group consisting of norflurazon, diflufenican,picolinafen, beflubutamid, fluridone, fluorochloridone and flurtamone.7. A method according to claim 2, wherein the herbicide is an ACCaseinhibitor.
 8. A method according to claim 7, wherein the herbicide isselected from the group consisting of clodinafop, pinoxaden, sethoxydim,clethodim, fluazifop-P-butyl, diclofop-methyl and fenoxaprop-P-ethyl. 9.A method according to claim 2, wherein the herbicide is an ALSinhibitor.
 10. A method according to claim 9, wherein the herbicide isselected from the group consisting of trifloxysulfuron, mesosulfuron,nicosulfuron, prosulfuron, chlorsulfuron, imazapyr, imazaquin,pyroxsulam, metosulam and pyriftalid.
 11. A method according to claim 2,wherein the herbicide is a PS-I inhibitor.
 12. A method according toclaim 11, wherein the herbicide is selected from the group consisting ofdiquat and paraquat.
 13. A method according to claim 2, wherein theherbicide is a PS-II inhibitor.
 14. A method according to claim 13,wherein the herbicide is selected from the group consisting of atrazine,simazine, terbuthylazine, bromacil, hexazinone, diuron, and bromoxynil.15. A method according to claim 2, wherein the herbicide is an EPSPSinhibitor.
 16. A method according to claim 15, wherein the herbicide isselected from the group consisting of glyphosate and sulfosate.
 17. Amethod according to claim 2, wherein the herbicide is a glutaminesynthetase inhibitor.
 18. A method according to claim 17, wherein theherbicide is selected from the group consisting of glufosinate-ammoniumand bialaphos.
 19. A method according to claim 2, wherein the herbicideis a synthetic auxin.
 20. A method according to claim 19, wherein theherbicide is selected from the group consisting of quinclorac, dicamba,fluoroxypyr, triclopyr and aminocyclopyrachlor.
 21. A method accordingto claim 2, wherein the herbicide is a PPO inhibitor.
 22. A methodaccording to claim 21, wherein the herbicide is selected from the groupconsisting of sulfentrazone, oxyfluorfen, lactofen, oxadiazon,fomesafen, saflufenacil and butafenacil.
 23. A method according to claim2, wherein the herbicide is a cellulose synthase inhibitor.
 24. A methodaccording to claim 23, wherein the herbicide is selected from the groupconsisting of dichlobenil, chlorthiamid, isoxaben and flupoxam.
 25. Amethod according to claim 2, wherein the herbicide is a microtubuleassembly inhibitor.
 26. A method according to claim 25, wherein theherbicide is selected from the group consisting of oryzalin,pendimethalin, trifluralin, dithiopyr and thiazopyr.
 27. A methodaccording to claim 2, wherein the herbicide is a VLCFA inhibitor.
 28. Amethod according to claim 27, wherein the herbicide is selected from thegroup consisting of acetochlor, s-metolachlor, pyroxasulfone andpretilachlor.
 29. A method according claim 2, wherein the plant growthregulator is selected from the group consisting of trinexapac-ethyl,prohexadione-calcium, paclobutrazol, flurprimidol, cyclocel, ethephon,mepiquat and chlomequat
 30. A method according to claim 29, wherein theplant growth regulator is a class A gibberellin biosynthesis inhibitor.31. A method according to claim 30, wherein the plant growth regulatoris trinexapac-ethyl.
 32. A method according to claim 2, wherein theweeds are monocotyledonous plants.
 33. A herbicidal compositioncomprising at least one herbicide and at least one plant growthregulator in a synergistically effective amount.
 34. A herbicidalcomposition according to claim 33, wherein the herbicide belongs to aclass selected from the group consisting of HPPD inhibitors, PDSinhibitors, ACCase inhibitors, ALS inhibitors, PS-I and PS-IIinhibitors, EPSPS inhibitors, glutamine synthetase inhibitors, syntheticauxins, PPO inhibitors, cellulose synthase inhibitors, microtubuleassembly inhibitors, and VLCFA inhibitors.